bandgap design -- curvature question

[micro86]

hi,

I have designed a bandgap, it works fine. one thing i noticed is in some process corner , the bandgap voltage keeps rising ( at typical it rises up and then curves down having zero TC@40C). can anyone tell me why this happens ?

bg is designed for -40 - 135C operation.

Thanks

 

[leo_o2]

That's normal. Corner variation might lead to bad TC compensation.

 

[dick_freebird]

Curvature comes from certain nonidealities, but there are others. Like
junction leakage, the gain effects within the amplifier of such leakage
and so on. And I've seen resistors that have unusual tempcos
that vary a lot with process (one that is sometimes cubic tempco and
other times, almost flat (its designed implant result).

This is why bandgap design is still a craft, 40 years later.